1. Field of the Invention.
This invention relates to relief valves and more particularly to a relatively large diameter rupture pin relief valve which is safely resettable in the field under pressure while flowing.
2. Description of the prior art.
I have successfully utilized a collapsible pin relief valve for monitoring fluid pressure in a conductor which opens under excess pressure in accordance with Euler's law for slender columns. The most pertinent patents are believed to be my U.S. Pat. Nos. 5,273,065 issued Dec. 28, 1993, and No. 5,348,039 issued Sep. 20, 1994, both for large diameter and a relatively high pressure relief valves. Both of these patents feature a relief valve having dual diameter pistons normally closing confronting open ends of axially aligned sleeves, and when moved to a valve open position, a piston rod is axially forced toward one end of a collapsible pin. The principal feature being the larger diameter piston partially balances out the pressure against the pin permitting the use of a smaller diameter pin to monitor fluid pressure. However, when one of these valves has opened in response to excess fluid pressure, it is necessary to reduce the fluid pressure in the conductor being monitored to near atmosphere in order to move the pistons toward a valve closed position before it is possible to insert a new collapsible pin.
This invention is distinctive over the above named valves by providing an auxiliary power assembly connected with the valve housing for moving the collapsible pin supporting elements from a pin collapsed position to a new pin receiving position with fluid pressure in the valve and conductor being monitored.